Ablation Study on Motion Modeling

Methods	Optimizes Camera Poses	Deformation Field	Deformable Objects	Root-body Initialization	Root-Body Motion
Ours	$$\checkmark$$	NBS	$$\checkmark$$	$$\checkmark$$	$$\checkmark$$
w/o cam. opt.	✗	NBS	$$\checkmark$$	$$\checkmark$$	$$\checkmark$$
w/ SE(3)-field	$$\checkmark$$	SE(3)-field	$$\checkmark$$	$$\checkmark$$	$$\checkmark$$
w/o deform. field	$$\checkmark$$	None	$$\checkmark$$	$$\checkmark$$	$$\checkmark$$
w/o root-body init.	$$\checkmark$$	NBS	$$\checkmark$$	✗	$$\checkmark$$
w/o root-body	✗	NBS	$$\checkmark$$	✗	✗
w/o root-body (SE3)	✗	SE(3)-field	$$\checkmark$$	✗	✗

• (w/o cam. opt.) Ablating camera-pose optimization does not qualitatively change the scene reconstruction.
• (w/ SE(3)-field) Changing the deformation field from Total-Recon's NBS (neural blend skinning) function to an SE(3)-field results in minor artifacts in the foreground reconstruction.
• (w/o deform. field) Removing the deformation field entirely produces coarse object reconstructions that fail to model moving body parts such as limbs.
• (w/o root-body init.) Removing PoseNet-initialization of root-body poses results in noisy appearance and geometry, and sometimes even failed object reconstructions.
• (w/o root-body) We do not visualize our method without root-body poses as this ablation does not converge.
• (w/o root-body (SE3)) We perform another ablation that replaces the NBS function with the more flexible SE(3)-field, which does converge but breaks foreground reconstruction entirely, as evidenced by the ghosting artifacts.

These experiments justify our method's hierarchical motion representation, where object motion is decomposed into global root-body motion and local articulations.

	Novel View (GT)	Ours	w/o cam. opt.	w/ SE(3)-field	w/o deform. field	w/o root- body init.	w/o root- body (SE3)
Human 2 & Cat 1
Human 1 & Dog 1
Dog 1
Cat 1
Cat 2
Human 1